Preparation of polyamic acids in ketone solvents

ABSTRACT

POLYAMIC ACIDS HAVE BEEN PREPARED BY THE INTERFACIAL POLYMERIZATION OF TRIMELLITOYL CHLORIDE WITH SULFONE ETHER DIAMINES BY ADDING A KETONE SOLUTION OF THE FORMER TO THE DIAMINE DISPERSED IN WATER CONTAINING AN HCL SCAVENGER WITH SHEARING AGITATION. THE POLYMERIZATION PROCEEDS RAPIDLY AND THE PRODUCT POLYAMIC-ACID CAN BE RECOVERED DIRECTLY FROM THE REACTION MIXTURE IN WHICH IT IS INSOLUBLE. THE POLYAMIC-ACID CAN THEN BE THERMALLY OR CHEMICALLY DEHYDRATED TO THE CORRESPONDING POLYAMIDEIMIDE.

United States Patent w 3,753,948 PREPARATION OF POLYAMIC ACIDS IN KETONE SOLVENTS George L. Brode, Somerville, and James H. Kawakami,

Piscataway, N.J., assignors to Union Carbide Corporation, New York, N.Y. No Drawing. Filed June 9, 1971, Ser. No. 151,597 Int. Cl. C08g 20/32 US. Cl. 260-49 7 Claims ABSTRACT OF THE DISCLOSURE Polyamic acids have been prepared by the interfacial polymerization of trimellitoyl chloride with sulfone ether diamines by adding a ketone solution of the former to the diamine dispersed in Water containing an HCl scavenger with shearing agitation. The polymerization proceeds rapidly and the product polyamic-acid can be recovered directly from the reaction mixture in which it is insoluble. The polyamic-acid can then be thermally or chemically dehydrated to the corresponding polyamideimide.

BACKGROUND OF THE INVENTION This invention pertains to a facile and rapid method of preparing high molecular weight polyamic acids and more particularly to the interfacial polymerization of trimellitoyl chloride with a sulfone ether diamine.

Previous methods of preparation of polyamic acids require the use of expensive solvents, anhydrous conditions, exact stoichiometries of the reactants and long reaction times. These methods also necessitate the recovery of the polyamic acids produced by coagulation from a non-solvent which require the recovery of the initial polymerization solvent via distillation steps addin to the overall expenses of the process.

Although interfacial polymerization techniques with diacid chlorides have been known, they have not been successfully applied to dianhydride monomers or anhydride acid-chlorides.

STATEMENT OF THE INVENTION A method for the preparation of polyamic-acids has now been found which does not require the use of anhydrous solvents and monomers of highest purity, does not require exact stoichiometry of the reactants, affords polyamic-acids which can be recovered quickly simply by filtration rather than by precipitation, and which affords high molecular weight polyamic-acids in relatively short polymerization times, that is, in the order of to 10 minutes.

This method comprises adding a solution of: (A) about 1 mole of trimellitoyl chloride dissolved in at least one normally liquid ketone selected from the class 3,753,948 Patented Aug. 21, 1973 consisting of aliphatic ketones having 1 to about 4 carbon atoms in each of the aliphatic moieties and cycloaliphatic ketones having about 5 to 8 carbon atoms to: (B) a mixture of about 1 mole of a sulfone ether diamine having the formula:

(E). wherein Ar is a divalent radical selected from the group consisting of wherein each E is a halogen substituent, and can be F, Cl, Br or I, each a is an integer having values of 0 to 4, R is an alkylidene radical having 1 to about 10 carbon atoms, and n is a rational number having values of 0 to 25 and about 0.9 to 2.0 moles of a hydrogen chloride scavenger dissolved in an aqueous solvent at a temperature of about 5 C. to about 100 C. with shearing agitation until normally solid polyamic acid forms.

Pressure is not critical and so super-atmospheric as well as sub-atmospheric pressures can be used although atmospheric pressure is preferred for economic reasons.

The polymerization can be carried out at temperatures of from about 5 to about 100 C. but it is preferred to provide the temperature range of about 25 to C.

Exemplary of the aliphatic ketones which can be used in this invention are methyl ethyl ketone, diethyl ketone, methyl propyl ketone, ethyl propyl ketone, methyl butyl ketone, ethyl butyl ketone, and the like Exemplary cycloaliphatic ketones include cyclopenta none, cyclohexanone, methylcyclopentanone, dimethylcyelopentanone, methylcyclohexanone, cycloheptanone, and the like.

Suitable hydrogen chloride scavengers include tertiary amines containing aliphatic substituents such as trimethylamine, triethylamine, tripropylamine, tributylamine, and the like. Other reagents which can be used include cyclic organic bases, such as, pyridine, lutidine, collidine, quinoline, and the like, inorganic bases such as alkali metal hydroxides, alkali metal carbonates, alkali metal acetates, alkaline earth oxide, alkaline earth hydroxides, alkaline earth carbonates, alkali earth acetates, and the like; and organic oxides such as ethylene oxide, propylene oxide, and the like.

Exemplary alkali metal hydroxides include sodium potassium, lithium and like hydroxides.

The reaction can be better understood by the sequence of reactions shown below between trimellitoyl chloride and a specific diamine.

l 2 a)aN 3 4 wherein x is a number representing the degree of polym- EXAMPLE 1 w p erization, and is sufficiently large so as to afford a normally solid high molecular weight polyamic acid. Preparation of S e ether d amme The agitation used during the polymerization reaction must be the shearing type keeping heterogeneous phases dispersed in small particles or globules as distinct from paddle type agitation which merely keeps a bulk in motion without vigorous intermixing. The shearing agitation required in the practice of this invention is provided by a Waring Blendor, Cowles Dissolver or any similar blend- 10 ing device having high speed, knife-edge mixing blades.

This reaction can be surprisingly employed with crude diamines and still affords high molecular weight polyamic acids. Solution of the diamine such as are obtained in the preparation of the diamine can even be added to the 1 polymerization reactor and the diarnine precipitated therein and used directly with no purification. Obviously, these advantages enhance the economics of the process. The diamines used in this invention can be prepared by the condensation of the sodium salt of p-aminophenol: (1) with 2 an equivalent amount of p-dichlorodiphenyl sulfone alone in one instance; (2) with an equimolar quantity of both A liter flask fitted with a mechanical stirrer, gas inlet tube, condenser, thermometer and Barrett tube was charged with 500 g. (4.58 moles) of p-aminophenol, 0.933 liter of dimethyl-sulfoxide and 1.2 liters of toluene. The solution was stirred under an argon atmosphere overnight after which time 36.94 g. (4.53 moles) of sodium hydroxide dissolved in sufficient water to atford a 49.00% aqueous solution was added. The water was removed from the toluene azeotrope which refluxed out ofthe flask as the temperature was raised gradually to 120 C. using the Barrett tube. At a pot temperature of 120 C. all of toluene was removed by distillation. The reaction mixture was cooled to 110 C. and 649.0 g. (2.26 moles) of diehlorodiphenylsulfone was added. The pot was heated to 160 C. for two hours and cooled to room temperature. The product, 4,4'-bis(p-oxyphenyleneamine) diphenyl sulfone was recovered by coagulation in water and amounted to 976 grams.

p-dichlorodiphenyl sulfone and bisphenol-A[2,2bis(p-hy- (B) 'Interfacial polymerization of sulfone etherdiamine droxyphenyl)propane], plus a further amount of p-dito polyamic acid chlorodiphenyl sulfone equivalent to the amount of the sodium salt of p-aminophenol used; and (3) with an equi- A one'quart WaFmg was charged wlth molar quantity of both p-dichlorodiphenyl sulfone and (0'06 mole) of Sodmm hydroxlde pdlets dlssqlveq m 200 hydroquinone plus an amount of p-dichlorodiphenyl sulof wafer and P sfllfcme Ftherdlamlne P fone equivalent to the amount of the sodium salt of p- Pare? as P A abovez W111]? stirring rapldly- Then aminophenol used 30 of trimelhtoyl chloride dissolved in 150 ml. of cyclo- These reactions are delineated in the equations below: hexanone was rapdly added to the blender- The reaction mixture rose in temperature to about 28 C. and turned very viscous. The agitation was ZHNQOML stopped after 15 minutes and the reaction mixture poured 5 into excess acetone, precipitating the polyamic acid. This HN so YH was filtered, washed with water and acetone and dried. I The polyamic acid was then dissolved in dimethylr e l .WQQ SO O SQ O NH, wherein m is a rational number having average product acetamide and converted to a polyamide-imide by imididistribution values ranging from 0 to about 25. V zation with a mixture of 10 ml. of acetic anhydride and Sim-Qua, mClQ-SOQOI (m+1 Ho- 0 wherein m is as defined above. 20 m1. of pyridine, stirring at room temperature over- The polyamic acids prepared by the claimed process night. The resultant polyamide-imide was coagulated in can be dehydrated to polyamide-imides either thermally acetone and dried at 100 C. in a vacuum oven overor chemically by the use of dehydrating agents such as, night. The yield was 18.1 grams. The reduced viscosity aliphatic acid anhydrides including acetic anhydride, of the polyamidefimide measured at a c ncent ation of halogenated compounds such as POCl or SOCI molee- 0.2 g. in 100 ml. of dimethylacetamide at 25 C. was 0.6. ular sieves, silica gel, phosphorous pentoxide, aluminum oxide, and the like. The resultant polyamide-imides are EXAMPLE 2 particularly useful for the fabrication of structural lami- A Waring Blendor was charged with a crude mixture nates and for the preparation of electric wire coatings, of 16.8 g. of sulfone etherdiamine in dimethyl sulfoxide dielectric films, molded parts, and the like. prepared as in Example 1A before coagulation, 100 ml.

The polyamic acids can also be used directly in the of water, 100 ml. of methylethyl ketone and 8.2 g. (0.039 above-described areas by depositing them directly or from mole) of triethylamine. Then a solution of 8.2 g. (0.039

solution on the appropriate substrate and then thermally mole) of trimellitoyl chloride in methylethyl ketone was dehydrating them to polyamide-imides. I added dropwise with rapid stirring. In ten minutes The invention is further described in the examples polyamic acid was filtered from the reaction mixture,

which follow. All parts and percentages are by weight unless otherwise specified.

washed with water and acetone and dried. The dried polyamic acid had a reduced viscosity of 0.28 when meas- 6 ured as 0.2 g. solution in 100 ml. of dimethylacetamide wherein Ar is a divalent radical selected from the group at 25 C. consisting of EXAMPLE 3 (E) (E)a (E)a When Example 1 is repeated with the exception that Q and a diamine having the formula: 5

is used, a polyarnide consisting essentially of repeating wherein each E is a halogen substituent, each a is an units have the following formula is obtained: integer having values of 0 to 4, R is an alkylidene radical wherein n is a number having a value sufiiciently higher having 1 to about 10 carbon atoms, and n is a rational so as to afford a normally solid polyamide-imide. number having values of 0 to about 25, and about 0.9 The polyamide-imides prepared as described above to 2.0 moles of a hydrogen chloride scavenger dissolved have mechanical and physical properties similar to the in an aqueous solvent, at a temperature of about 5 C. polyamides-imides described in Ser. No. 50,968 now to about 100 C. with shearing agitation until a normally abandoned which is incorporated herein by reference. solid polyamic acid forms.

Although the invention has been described in its 2. Method claimed in claim 1 wherein m=1, a=0, preferred forms with a certain degree of particularity, and Ar is it is understood that the present disclosure of the pre- (Eh (E)a ferred forms has been made only by way of example and that numerouschanges may be resorted to without de- G Q parting from the spirit and the scope of the invention.

What is claimed s: 3. Method claimed in claim 2 wherein R is an iso- 1. A method for the preparation of polyamic acids lid di l, which Comprises adding! a Solution of about One 4. Method claimed in claim 1 wherein the normally mole of trimellitoyl chloride dissolved in at least one li id k i an li h tic ketone normally liquid ketone selected from the class consisting 5 M th d l imed in laim 1 wherein the hydrogen of aliphatic ketones having 1 to about 4 carbon atoms in hl id v er i triethylamine. each of the aliphatic moieties and cycloaliphatic ketones 6, M hod laimed in claim 1 wherein the hydrogen having about 5 to 8 carbon atoms to: (B) a mixture 0f chloride scavenger is an alkali metal hydroxide. about one mole of sulfone ether diamine having the 7. Method claimed in claim 1 wherein the temperature formula: is about 25 C. to about C.

References Cited UNITED STATES PATENTS 3,428,602 2/ 1969 Haller 26047 3,652,498 3/1972 Morello et al. 260-47 3,658,938 4/1972 Kwiatkowski et a1. 260857 OTHER REFERENCES Y. Imai et al., Journal of Polymer Science, Part B, vol. 8, No. 8, pp. 559-562, August 1970.

WILLIAM H. SHORT, Primary Examiner L. L. LEE, Assistant Examiner U.S. Cl. X.R. 260-78 TF 

